1. Field of the Invention
The present invention relates to telecommunication networks, and more specifically to a system, method, and network for providing high speed remote access from any location connected by a local loop to a central office.
2. Related Art
Remote access generally refers to the ability of a user to access a remote system using a local system (e.g., a personal computer). The remote system can be either a stand-alone system or a network of systems. Mainframe computers such as those available from International Business Machines is an example of a stand-alone system. A network connecting several systems such as printers, modems, servers, computer systems, telecommunication equipment, among others, is an example of a network of systems. Remote access is commonly referred to as internet access when a local system accesses a remote network of systems such as what it known as world-wide-web.
Remote access typically requires transferring digital data between a local system and a remote system. Several applications and/or services with varying degrees of complexity can be provided using the remote access feature. Electronic mail, web browsing, distributed database applications, and electronic commerce are examples of such applications and services.
There has been an increasing demand for higher bandwidth connections from locations such as homes and small businesses. The need for higher bandwidth from homes has been driven in some instances by tele-commuters (employees working from homes) who would like to enjoy similar response times from corporate computer resources as their in-office counterparts when transferring files, accessing data bases etc.
In addition, it is believed that the availability of higher bandwidth will drive the market to provide more multimedia applications over the remote access connections. Large bandwidth connections may allow small businesses to disseminate (e.g., by providing a web server locally) or receive more information quickly from external customers or companies.
One solution for providing high-bandwidth connections to homes and small business is to install fibre to every location of interest. Unfortunately, installation of fibre to every home and small business is expensive and time consuming, thereby making it unsuitable for immediate deployment.
Another solution which has been attempted is to provide high bandwidth connections over cable installed for broadcasting television programs. The physical media (cable) is shared by many users from different homes and businesses. Unfortunately, such sharing may lead to unpredictability in the bandwidth available to individual users because high usage by some users may leave very little bandwidth for the others. In addition, due to the shared nature of the underlying media, users may be concerned about security and privacy.
Yet another option is to use the physical connections already installed for providing voice telephone calls over the past several decades. Voice telephone calls have been typically provided over metallic (e.g., copper) pairs connecting to homes (and small businesses). These physical connections are commonly referred to as local loops. The local loops originate at what is known as a "central office" in the United States Telecommunications industry.
Remote access using local loops overcomes at least the disadvantages noted with reference to fibre and cable. That is, local loops have been already installed over the past several decades and they can be used immediately. In addition, each local loop is dedicated to a home or business, leading to less unpredictability in the bandwidth availability due to active use by other users.
The local loops have bee installed originally to provide connections to voice calls placed from telephone instruments in locations such as homes and offices. To provide connections for voice calls, the local loops terminating at central offices are usually connected to a voice switch (e.g., 5ESS from Lucent Technologies, 600 Mountain Avenue, Murray Hill, N.J. 07974, USA, URL:www.lucent.com, Phone Number:1-908-582-8500). A sequence of voice switches in tandem provides the basic connection for a voice call, with the last voice switch in the sequence being connected to the target (destination) telephone instrument. In general, voices switches are expensive due to the requirement to provide different types of services (e.g., switched voice calls, 9-1-1 emergency calls etc.).
Attempts have been made in the industry to provide as high bandwidth as, possible for remote access using the basic telecommunication infrastructure installed for voice calls. In a typical configuration, a home computer uses a modem to communicate with a remote system. The modem converts digital data to be transmitted from the home computer into analog signals suitable for transmission over a local loop. A remote computer uses another modem to receive the analog signals and converts back the received analog signals into digital data using another modem. The data transfer occurs in the reverse direction (i.e., from remote computer to home computer) also to support the remote access.
Unfortunately, the bandwidth rates which can be supported on local loops used as switched voice lines (i.e., using modems) is limited. Modems and remote access equipment supporting bandwidth as high as 56 Kbps (at least in one direction) have been available from companies such as 3COM corporation and Ascend Communications. Much higher bandwidth is believed to be hard to achieve on a single local loop, at least in a cost-effective manner through switched voice switches.
Bandwidth of the order of 56 Kbps may not be sufficient for some users at homes and for many small businesses. The remote access requirements for homes and small businesses typically include availability of reasonably high speed remote access at a fairly low price for affordability. Users from these types of locations usually do not have the resources to invest in special equipment (e.g., a fibre line and associated equipment) for high bandwidth. Therefore, it may be an important requirement to provide high bandwidth over the local loops described briefly above.
To provide higher bandwidth to locations connected by local loops, a group of technologies commonly referred to as digital-subscriber-loop (DSL) technologies have evolved. The DSL technologies only as applicable to the present invention are described here. For a detailed description of the various DSL technologies, the reader is referred to "Residential Broadband", by George Abe, published by Cisco Press, ISBN:1-57870-020-5, which is incorporated in its entirety herewith.
According to the DSL group of technologies, a local loop is generally dedicated for use with DSL technologies. Bandwidth higher than that possible through modem based service can be provided using these group of technologies. The bandwidth which can be provided is typically limited by the distance, the media used to implement the physical connection, potential presence of factors causing noise, and the signaling scheme chosen for the corresponding DSL technologies.
Of the DSL group of technologies, IDSL (DSL technology using basic ISDN signaling framework) can be used to provide bandwidth of 128 Kbps or 144 Kbps depending on the type of IDSL implementation. All local loops to homes can be equipped to support the IDSL signaling scheme irrespective of the distance a home is from the central office. Therefore, every location connected with a local loop can usually be provided remote access with a bandwidth of 128 Kbps or 144 Kbps. However, 128 Kbps or 144 Kbps bandwidth may not be sufficient for many locations. For example, some users at homes or small businesses may need much more than the 128 Kbps or 144 Kbps bandwidth possible using IDSL technology.
Asymmetric DSL (ADSL) is another one of the DSL group of technologies, which allows such higher bandwidth connections. As an illustration, DMT-modulated ADSL technology can support bandwidth of 6.1 Mbps in the direction leaving the central office and 640 Kbps in the reverse direction. ADSL has the general requirements that a location connected with a local loop needs to be within 14,000 feet (approximately 3 miles) of the central office and that the local loop be a continuous metallic path (without electronic transmission equipment) end-to-end (i.e., from home to central office) to a location.
Unfortunately, not all the locations (homes and businesses) meet both the requirements for ADSL. Some homes and businesses may be outside of the 3 mile range from a central office. In some other situations, the underlying local loop may not have a metallic path end-to-end. For example, the metallic wires terminating at locations such as office buildings and apartment complexes ("multiple family dwellings") typically originate at a multiplexor commonly known as digital loop carrier (DLC), and DLCs are connected to central offices through shared media as described briefly below with reference to an apartment complex including several apartments.
In a typical scenario, a DLC is placed within or close to an apartment complex. The DLC is usually connected to the central office using fibre or two pairs of metallic wires. A, bandwidth of at least T1 is generally provided between the DLC and the central office, and the data required to support connections to each telephone instrument in an apartment is multiplexed on the provided bandwidth. In some scenarios, ADSL cannot be supported due to the limited bandwidth (e.g., T1) available between DLCs and central offices. Even with the availability of substantial higher bandwidth between a central office and DLC, special hardware and/or software may be required in the DLC. Such special hardware and/or software may not be available in many DLCs. Accordingly, it may not be possible to provide ADSL based connections to several apartments.
At least from the above, it should be appreciated that high bandwidth connections may be provided using the DSL technologies. A provider may provide high bandwidth connections using either the IDSL technology alone or ADSL technology alone. The provision of high speed connection using only one of these technologies leads to several disadvantages. Some example disadvantages are noted below.
When the bandwidth is provided using only one of the DSL technologies, a service provider may not have the ability to provide high speed remote access to all locations connected to a central office by local loops. For example, a provider using only the ADSL technology may not be able to serve locations connected through DLCs and locations away from central offices by more tan three miles due to reasons described above. On the other hand, a provider using only the IDSL technology may not be able to serve subscribers requiring bandwidtl larger than 144 Kbps or 128 Kbps. As a result, the pool of potential subscribers is smaller than all the locations connected to a central office with local loops.
The smaller pool of potential subscribers in turn can lead to more disadvantages. For example, many large companies may be discouraged from subscribing to the service due to the unavailability of high speed remote access to all their employees. As a result, some large companies may not even subscribe to the service providers providing high speed remote access using only either ADSL or IDSL technology. Subscription by less companies generally leads to an even smaller pool of actual subscribers.
The cost of providing services is higher in such instances as `economies of scale` may not be recognized due to the smaller pool of subscribers. Economy of scale refers to the generally understood notion in the telecommunications industry that the average cost to provide a given service to a large pool of consumers is less than the average cost to provide the same service to a smaller pool of consumers. The increased cost due to the small pool of actual subscribers may be unacceptable in some situations.
Therefore, what is needed is a cost-effective scheme to provide high speed remote access to any location connected to a central office.